Here is a great web site on the Mansi people of Western Siberia. Many Mansi carry the U4 Haplogroup.
The Mansi - History and Present Day
Aado Lintrop, Institute of the Estonian Language
Ugria (Yugra or Yura) is mentioned already in the works of old Arabian authors. The missionary and traveller Al Garnati writes: "But beyond Visu by the Sea of Darkness there lies a land known by the name of Yura. In summers the days are very long there, so that the Sun does not set for forty days, as the merchants say; but in winters the nights are equally long. The merchants report that Darkness is not far (from them), and that the people of Yura go there and enter it with torches, and find a huge tree there which is like a big village. But on top of the tree there sits a large creature, they say it is a bird. And they bring merchandise along, and each merchant sets down his goods apart from those of the others; and he makes a mark on them and leaves, but when he comes back, he finds commodities there, necessary for his own country…" (Al Garnati:32). If the country called Visu has been identified with ancient Vepsaland (due to linguistic affinity with the Russian word for Vepsans, 'ves') or with Perm (due to geographical vicinity with Yugra), Yugra itself has been unanimously associated with the Ob-Ugrians - the Khanty and the Mansi. In the giant tree mentioned by Al Garnati we can recognise the World Tree, familiar from the mythologies of various North-European peoples. Some authors have also related the following report of Al Garnati's to the Ugrians: "And from Bulgar merchants travel to the land of heathens, called Visu; marvellous beaver skins come from there, and they take there wedge-shaped unpolished swords made in Aserbaijan in their turn… But the inhabitants of Visu take these swords to the land that lies near the Darkness by the Black Sea, and they trade the swords for sable skins. And these people take the swords and cast them into the Black Sea; but Allah the Almighty sends them a fish which size is like a mountain; and they sail out to the fish in their ships and carve its flesh for months on end." (ibid:58-59). Nevertheless, it ought to be clear that the vicinity of the Darkness and the Black Sea (the polar regions and the Arctic Ocean) is not characteristic of Ugria alone, and that the last report regards peoples who derived a substantial part of their livelihood from whaling.